Arc-lamp having magnetizable electrodes.



G. M. LITTLE.

ARC LAMP HAVING MAGNETIZABLE ELEGTRODES. APPLICATION FILED MAY 10, 1906.

933,769. Patented Sept. 14,1909. E1 14.

M ATTORNEY Gnonen M. LITTLE, or rirrssune, PENNSYLVANIA, assrenon 1'0.wnsr-rnenousn ELECTRIC & MANUFACTURING COMPANY, A CORPCEATION OFPENNSYLVANIA.

ARC-LAMP HAVING- MAGNETIZABLE ELECTRODES.

Specification of Letters Patent. Patgnited Sept, 14, jlgtlg.

Application filed May 10, 1908. Serial No. 316,134.

T 0 all whom it may concern:

Be it known that I, GEORGE M. Lrr'rLn, a citizen of the United States,and a resident of Pittsburg, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Arc-LampsHaving Magnetizable Electrodes, of which the following is aspecification.

My invention relates to are lamps and particularly to those in whichelectrodes containing magnetizable materials are employed.

The object of my invention is to provide means for neutralizing magneticfields that may be produced by external means in electrodes of thecharacter indicated.

Electrodes for are lamps are frequently composed of magnetic oxid ofiron and oxids of titanium and chromium, or of other suitablesubstances, that are contained in iron tubes. In the use of suchelectrodes it has been found that the arc is frequently distorted andlengthened to such a degree as toseriously interfere with the operationof the lamp, and I have discovered that the distortion and lengtheningof the arc has been the result of the magnetization of the electrodes bystray magnetic fields from the operating magnets of the lamps.

According to the present invention I propose to neutralize the straymagnetic fields by placing either a permanent or an electromagnet in asuitable relation to the magnetizable electrode.

Figure 1 of the' accompanying drawing is a view in elevation of an arclamp that embodies my invention, a portion of the casing being brokenaway for the sake of clearness of illustration, and Fig. 2 is adiagrammatic view of the circuits of the lamp of Fig. 1.

An electrode 1, that may be composed mainly of magnetic oxid of iron andoxide of titanium and chromium, or of other. suit able materials,contained-within an iron or other magnetic tube 2, is adapted to bemoved downwardly into engagement with a stationary electrode 3 and to beadjusted in position with reference thereto by any suitable meansgenerally employed for this purpose. As here shown, the electrode issupported by means of" a clutch 4 that may be moved downwardly againstthe tension of a spring 5 by means of an electro-magnet having a winding6. A pair of contact terminals 7 and 8 are interposed in the circuit ofthe magnet winding (5 and are adapted to be electrically connected bymeans of either of switch members 9 and 10, the former of which engagesthe contact terminals when no current is supplied to the lamp. Theswitch member 9 is provided with an operating magnet winding 11 that isconnected in series with the electrodes 1 and 3, and the switch member10 is provided with an operating magnet winding 12 of comparatively highresistance the terminals of which are connected to the contact terminals7 and 8.

W'hen current is suppliedto the lamp it first traverses magnet winding6, a resistance 13, and switch member 9. The clutch a: and the electrode1 will then be moved downwardly until the latter engages the electrode3, when a circuit will be established through the electrodes 3 and 1, acoil l l, and the winding 11. The winding 11 thereupon raises the switchmember 9 and the high resistance winding 12 is thereby included incircuit with the winding 6.

The magnetizing efiect thus becomes so much reduced that the spring 5 ispermitted to raise the clutch 4n and separate the electrodes 1 and 3. Anarc is thus started which continues until the voltage applied to thewinding 12 is increased to such an extent, by reason of the lengtheningof the distance between the electrodes, as to enable its magnetizingefiect to raise the switch member 10, when the circuit of the magnetwinding 6 will be established in the same manner as when starting.

lit will be observed that the magnet windings of the lamp are located insuch close proximity to the upper end of electrode 1 that stray magneticfields may magnet-12c the magnetizable materials and the iron shell ofthe upper electrode. lln order to prevent the distortion and lengthenmgof the are which has heretofore occurred as a result of themagnetization of the electrode,

vary approximately in proportion to the that may be produced therein byexternal stray magnetism. means comprising an eieotro-magnet wind- 1claim as my invention: I ing that surrounds the electrode. 1. Thecombination with an arc lamp In testimony whereof, I have hereunto 15electrode that contains magnetizable masubscribed my name this 1st dayof Maya tielriall, of a magnet inding that surrounlds 1906-. v

t e e ectrode and is connected in series re ation therewith GEORGE M.LITTLE.

2. The vcombination with an arc lamp Witnesses:

electrode that contains magnetizable ma- OTTO S. SOHAiRER;

terial, of means for neutralizing magnetism BIRNEY HINES:

